珠江口附近春季一次海雾的观测分析及三维数值模拟

An observational analysis and 3-dimensional numerical simulation of a sea fog event near the Pearl River Mouth in boreal spring

为了探讨南海春季海雾的成因及数值模式的预报能力,利用边界层观测资料对2006年3月21—22日珠江口附近春季一次海雾的形成和发展过程进行了分析,然后用WRF中尺度模式对该次海雾过程进行了三维数值模拟。观测表明,该次海雾属于北方冷空气南下到达南海,然后减弱消失,南海北部受到偏南暖湿气流影响后迅速增暖,冷海面与近海面的暖湿空气相互作用而形成的一次平流冷却雾。模拟结果显示,模式模拟的这次海雾形成时间和发展演变过程与观测非常相近,模拟的海雾空间变化、边界层大气层结变化、地面感热通量变化以及海雾形成原因与观测事实均比较吻合,数值模式对这次海雾过程表现出了较高的模拟能力。这次海雾的形成和发展主要与冷的下垫面、暖湿空气的影响和近地面稳定的大气层结有关。

For exploring the causes of sea fog over the South China Sea in boreal spring and the forecast capability of a numerical model,the observational data of atmospheric boundary layer are employed,and the formation and development processes of a sea fog event near the Pearl River Mouth in boreal spring between 21 and 22 March 2006 are analyzed.Then the 3-dimensional numerical simulation is carried out on the process of this sea fog by using the Weather Research and Forecasting（WRF） mesoscale model.The observational results show that this sea fog belongs to an advection cooling fog.It was caused by the cold air from north moving into the South China Sea and then weakening and disappearing when the north of the South China Sea was influenced by the southern warm-wet air flow with the air temperature warming up rapidly.And it was a result of interaction between cold sea surface and warm-wet air.The simulation results show that the forming time and process of developing evolution of this sea fog are very close to the observational result.The spatial change of this sea fog,the atmospheric stratification change of boundary layer,the change of surface sensible heat flux and the formation cause of this sea fog simulated by the model are all relatively consistent with the observational fact.And the numerical model shows a good simulation skill and ability on the process of this sea fog.This sea fog＇s formation and development mainly have some connection with the cold underlying surface,the influence of warm and wet air,and the stable atmospheric stratification near ground.